This invention concerns a metal strip for the manufacture of elements for the exchange of sensible and latent heat from a warm outgoing air stream to a cold ingoing air stream in a regenerative heat exchanger, in which, for example, corrugated and flat sheets are alternatively combined to form flow channels.
In such regenerators component parts which are heated by the heat in the air passing over them give off this energy again to the cold air subsequently drawn over them. In this connection, it has been found that the transfer of both latent heat and sensible heat is very energy saving.
For such regenerative heating, use is made of rotating heat exchangers which have disc-shaped rotary units of flat and corrugated sheet or foil made of metal, asbestos or plastic but which have not been able to achieve optimum performance up to now. Metallic foils transfer sensible heat very well but, with respect to transfer of the latent heat, which results from the condensation of moisture from steam, they have a low efficiency. Asbestos blades achieve a better heat transfer from the condensed water but, because of the hazard it represents, asbestos cannot be used in ventilator systems.
Attempts have been made to overcome the disadvantage of metal rotary units, i.e., the poor absorbtion of moisture, by treating the blades with lithium chloride; the purpose of the resultant crystals on the metallic elements is to assist the conversion of steam to water.
The main problem of such regenerators lies in their manufacture in that the regenerator has to be treated to form the crystals after the metallic elements have been built into a heat exchanger. Also, it is doubtful whether such treatments to improve the absorption of moisture are adequate.